Exists

 
public final class Exists<F>

Encodes the notion of existential type. Exists<F> is a wrapper around a Kind<F, X> value, where X is some type that is not exposed on Exists signature.

You provide a value of type Kind<F, X> when constructing an Exists<F>instance but the specific type X that you provide is hidden inside Exists. The only way to interact with the content of Exists<F> is with a function of type Kind<F, X> -> R that is polymorphic on X (represented by the CokleisliK<F, R class). You pass a CokleisliK<F, R> to an Exists<F> and the function is called with the specific type that is hidden inside the Exists. This is done with the run method.

  • Construct and Exists from a value of type Kind<F, A> and hide it’s type parameter A.

    Declaration

    Swift

    public init<A>(_ fa: Kind<F, A>)

  • Process the contents of this Exists with a function of type Kind<F, X> -> R that is polymorphic on X.

    Declaration

    Swift

    public func run<R>(_ f: CokleisliK<F, R>) -> R

  • Declaration

    Swift

    public var description: String { get }